CN117955444A

CN117955444A - Load modulated radio frequency amplifier with extended tuning range

Info

Publication number: CN117955444A
Application number: CN202311417959.0A
Authority: CN
Inventors: S·亨茨勒; A·兰格
Original assignee: Apple Inc
Current assignee: Apple Inc
Priority date: 2022-10-31
Filing date: 2023-10-30
Publication date: 2024-04-30

Abstract

The present disclosure relates to load modulated radio frequency amplifiers with extended tuning ranges. An electronic device may include a wireless circuit having: an amplifier configured to receive a radio frequency signal generated from a baseband signal; a first adjustable load component coupled to an output of the amplifier; a second adjustable load component coupled to the output of the amplifier; and a control signal generator configured to output one or more control signals for tuning the first and second adjustable load components based on an envelope of the baseband signal or the radio frequency signal. The first adjustable load component may provide a first tuning range covering a first sub-range of the instantaneous signal envelope of the baseband signal or the radio frequency signal, and the second adjustable load component may provide a second tuning range covering a second sub-range of the instantaneous signal envelope of the baseband signal or the radio frequency signal. The first tuning range and the second tuning range combine to provide an extended tuning range.

Description

Load modulated radio frequency amplifier with extended tuning range

The present application claims priority from U.S. patent application Ser. No. 18/296,295, filed on 5 at 4 at 2023, and U.S. provisional patent application Ser. No. 63/421,075, filed on 31 at 10 at 2022, which are incorporated herein by reference in their entireties.

Technical Field

The present disclosure relates generally to electronic devices, and more particularly to electronic devices having wireless communication circuitry.

Background

Electronic devices often have wireless communication capabilities. An electronic device with wireless communication capability has wireless communication circuitry with one or more antennas. Wireless transceiver circuitry in a wireless communication circuit uses antennas to transmit and receive radio frequency signals.

The radio frequency signals transmitted by the antenna may be fed through one or more power amplifiers configured to amplify the low power analog signals into higher power signals more suitable for long distance transmission through air. Designing a satisfactory power amplifier for an electronic device can be challenging.

Disclosure of Invention

The electronic device may include wireless communication circuitry. The wireless communication circuit may include: one or more processors or signal processing blocks for generating baseband signals; a transceiver for receiving a digital signal and for generating a corresponding radio frequency signal; and one or more radio frequency power amplifiers configured to amplify the radio frequency signal for transmission through one or more antennas in the electronic device. At least one of the radio frequency power amplifiers may be implemented as a load line modulated radio frequency amplifier circuit. The load line modulated radio frequency amplifier circuit may include an amplifier core coupled to one or more adjustable load impedances.

An aspect of the present disclosure provides a wireless circuit including: a radio frequency amplifier configured to receive a radio frequency signal generated from a baseband signal; a first adjustable load component coupled to an output of the radio frequency amplifier; a second adjustable load component coupled to the output of the radio frequency amplifier; and a control signal generator configured to output one or more control signals for tuning the first and second adjustable load components based on an envelope of the baseband signal or the radio frequency signal. The first adjustable load component may be configured to provide a first impedance tuning range for a first sub-range of the envelope, and the second adjustable load component may be configured to provide a second impedance tuning range for a second sub-range of the envelope. The first adjustable load component and the second adjustable load component may be coupled to the output of the radio frequency amplifier via a first coupling circuit and a second coupling circuit, respectively, or via a joint coupling circuit.

An aspect of the present disclosure provides a method of operating a wireless circuit, the method comprising: receiving, at an amplifier, a radio frequency signal generated based on the baseband signal; tuning a first adjustable load component located at an output of the amplifier using a first load tuning control signal derived from an envelope of the baseband signal or the radio frequency signal; and tuning a second adjustable load component located at the output of the amplifier using a second load tuning control signal derived from the envelope of the baseband signal or the radio frequency signal. The first adjustable load component may be operable to provide a first impedance tuning range for a first sub-range of the envelope, and the second adjustable load component may be operable to provide a second impedance tuning range for a second sub-range of the envelope that is different from the first impedance tuning range. The control signal generator may be configured to generate a control signal based on the baseband signal or the envelope of the radio frequency signal. The first conversion circuit may be operable to output the first load tuning control signal based on a first range of the control signal, and the second conversion circuit may be operable to output the second load tuning control signal based on a second range of the control signal. The second control signal may be offset from the first control signal by a fixed or adjustable offset.

An aspect of the present disclosure provides an electronic device including: one or more processors configured to generate a baseband signal; an up-converter configured to convert the baseband signal to a radio frequency signal; and a load line modulation amplifier circuit configured to amplify the radio frequency signal. The load line modulation amplifier circuit may include: an amplifier configured to receive the radio frequency signal; a first adjustable load component coupled to the output of the amplifier and configured to provide a first tuning range covering a first sub-range of the instantaneous signal envelope of the baseband signal or the radio frequency signal; and a second adjustable load component coupled to the output of the amplifier and configured to provide a second tuning range covering a second sub-range of the instantaneous signal envelope of the baseband signal or the radio frequency signal. The first tuning range and the second tuning range combine to provide an extended tuning range for the load line modulated amplifier circuit.

Drawings

Fig. 1 is a diagram of an exemplary electronic device with wireless circuitry according to some embodiments.

Fig. 2 is a diagram of an exemplary radio circuit with an amplifier, according to some embodiments.

Fig. 3 is a diagram of an exemplary radio circuit having a load modulation amplifier with multiple adjustable load components, according to some embodiments.

Fig. 4 is a circuit diagram of an exemplary load modulation amplifier connected to at least two adjustable load components via a coupling circuit, according to some embodiments.

Fig. 5 is a graphical representation of amplifier load impedance plotted as a function of control voltage signal for tuning the adjustable load component of fig. 4, according to some embodiments.

Fig. 6 is a diagram showing how an adjustable load component may have partially overlapping tuning ranges, according to some embodiments.

Fig. 7 is a diagram of an exemplary load modulation amplifier coupled to at least three adjustable load components having three separate tuning ranges, according to some embodiments.

Fig. 8 is a state diagram illustrating how a load modulated amplifier may be able to operate in multiple Adaptive Power Tracking (APT) modes, according to some embodiments.

Detailed Description

An electronic device, such as device 10 of fig. 1, may be provided with wireless circuitry. The wireless circuit may include a processor for generating a baseband signal, an up-conversion circuit for up-converting (mixing) the baseband signal to a radio frequency signal, an amplifier for amplifying the radio frequency signal, and an antenna for radiating the amplified radio frequency signal.

The amplifier may be a load modulated radio frequency power amplifier having a plurality of adjustable load components each configured to cover a different modulation range. Load modulated radio frequency amplifiers are sometimes referred to as Load Line Modulated (LLM) power amplifiers. A first one of the adjustable load components may be used to provide impedance tuning that covers a first sub-range of the instantaneous signal envelope of the baseband signal, while a second one of the adjustable load components may be used to provide impedance tuning that covers a second sub-range of the instantaneous signal envelope of the baseband signal. The use of multiple adjustable load components may collectively provide a wider effective load (impedance) tuning range for the load-modulated radio frequency amplifier.

The electronic device 10 of fig. 1 may be: computing devices such as laptop computers, desktop computers, computer monitors including embedded computers, tablet computers, cellular telephones, media players, or other handheld or portable electronic devices; smaller devices such as wristwatch devices, hanging devices, earphone or earpiece devices, devices embedded in eyeglasses; or other equipment worn on the user's head; or other wearable or miniature devices, televisions, computer displays that do not contain embedded computers, gaming devices, navigation devices, embedded systems (such as systems in which electronic equipment with displays is installed in kiosks or automobiles), voice-controlled speakers connected to the wireless internet, home entertainment devices, remote control devices, game controllers, peripheral user input devices, wireless base stations or access points, equipment that implements the functionality of two or more of these devices; or other electronic equipment.

As shown in the functional block diagram of fig. 1, device 10 may include components located on or within an electronic device housing, such as housing 12. The housing 12 (which may sometimes be referred to as a shell) may be formed of plastic, glass, ceramic, fiber composite, metal (e.g., stainless steel, aluminum, metal alloys, etc.), other suitable materials, or a combination of these materials. In some embodiments, some or all of the housing 12 may be formed of a dielectric or other low conductivity material (e.g., glass, ceramic, plastic, sapphire, etc.). In other embodiments, the housing 12 or at least some of the structures making up the housing 12 may be formed from metal elements.

The device 10 may include a control circuit 14. The control circuit 14 may include a memory device, such as the memory circuit 16. The storage circuitry 16 may include hard drive storage, non-volatile memory (e.g., flash memory or other electrically programmable read-only memory configured to form a solid state drive), volatile memory (e.g., static random access memory or dynamic random access memory), and the like. The storage circuitry 16 may include storage and/or removable storage media integrated within the device 10.

The control circuit 14 may include processing circuitry, such as processing circuitry 18. The processing circuitry 18 may be used to control the operation of the device 10. The processing circuitry 18 may include one or more microprocessors, microcontrollers, digital signal processors, host processors, baseband processor integrated circuits, application specific integrated circuits, central Processing Units (CPUs), and the like. Control circuitry 14 may be configured to perform operations in device 10 using hardware (e.g., dedicated hardware or circuitry), firmware, and/or software. The software code for performing operations in the device 10 may be stored on the storage circuitry 16 (e.g., the storage circuitry 16 may comprise a non-transitory (tangible) computer-readable storage medium storing the software code). The software code may sometimes be referred to as program instructions, software, data, instructions, or code. Software code stored on the memory circuit 16 may be executed by the processing circuit 18.

Control circuitry 14 may be used to run software on device 10 such as satellite navigation applications, internet browsing applications, voice Over Internet Protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, and the like. To support interaction with external equipment, the control circuit 14 may be used to implement a communication protocol. Communication protocols that may be implemented using control circuitry 14 include: internet protocol, wireless Local Area Network (WLAN) protocol (e.g., IEEE 802.11 protocol-sometimes referred to as) Protocols for other short-range wireless communication links such asProtocols or other Wireless Personal Area Network (WPAN) protocols, IEEE 802.11ad protocols (e.g., ultra wideband protocols), cellular telephone protocols (e.g., 3G protocols, 4G (LTE) protocols, 5G protocols, etc.), antenna diversity protocols, satellite navigation system protocols (e.g., global Positioning System (GPS) protocols, global navigation satellite system (GLONASS) protocols, etc.), antenna-based spatial ranging protocols (e.g., radio detection and ranging (RADAR) protocols or other desired range detection protocols for signals transmitted at millimeter and centimeter wave frequencies), or any other desired communication protocol. Each communication protocol may be associated with a corresponding Radio Access Technology (RAT) that specifies the physical connection method used to implement the protocol.

The device 10 may include an input-output circuit 20. The input-output circuit 20 may include an input-output device 22. The input-output device 22 may be used to allow data to be supplied to the device 10 and to allow data to be provided from the device 10 to an external device. The input-output devices 22 may include user interface devices, data port devices, and other input-output components. For example, the input-output devices 22 may include touch sensors, displays (e.g., touch-sensitive and/or force-sensitive displays), lighting components such as displays without touch sensor capabilities, buttons (mechanical, capacitive, optical, etc.), scroll wheels, touch pads, keypads, keyboards, microphones, cameras, buttons, speakers, status indicators, audio jacks and other audio port components, digital data port devices, motion sensors (accelerometers, gyroscopes, and/or compasses that detect motion), capacitive sensors, proximity sensors, magnetic sensors, force sensors (e.g., force sensors coupled to the display to detect pressure applied to the display), and the like. In some configurations, keyboards, headphones, displays, pointing devices such as touch pads, mice, and joysticks, and other input-output devices may be coupled to the device 10 using wired or wireless connections (e.g., some of the input-output devices 22 may be peripheral devices coupled to a main processing unit or other portion of the device 10 via wired or wireless links).

The input-output circuitry 20 may include wireless circuitry 24 to support wireless communications. The wireless circuitry 24 (sometimes referred to herein as wireless communications circuitry 24) may include one or more antennas. The wireless circuitry 24 may also include baseband processor circuitry, transceiver circuitry, amplifier circuitry, filter circuitry, switching circuitry, radio frequency transmission lines, and/or any other circuitry for transmitting and/or receiving radio frequency signals using an antenna.

The wireless circuitry 24 may transmit and/or receive radio frequency signals within a corresponding frequency band of radio frequencies (sometimes referred to herein as a communication band or simply "band"). The frequency bands processed by wireless circuitry 24 may include Wireless Local Area Network (WLAN) frequency bands (e.g.,(IEEE 802.11) or other WLAN communication bands) such as the 2.4GHz WLAN band (e.g., 2400MHz to 2480 MHz), the 5GHz WLAN band (e.g., 5180MHz to 5825 MHz),/>6E band (e.g., 5925MHz to 7125 MHz) and/or other/>Frequency bands (e.g., 1875MHz to 5160 MHz); wireless Personal Area Network (WPAN) bands such as 2.4GHz/>Frequency bands or other WPAN communication bands; cellular telephone bands (e.g., bands of about 600MHz to about 5GHz, 3G bands, 4G LTE bands, 5G new air interface frequency range 1 (FR 1) bands below 10GHz, 5G new air interface frequency range 2 (FR 2) bands between 20GHz and 60GHz, etc.); other centimeter or millimeter wave bands between 10GHz and 300 GHz; near field communication band (e.g., 13.56 MHz); satellite navigation frequency bands (e.g., GPS frequency band 1565MHz to 1610MHz, global satellite navigation System (GLONASS) frequency band, beidou satellite navigation System (BDS) frequency band, etc.); an Ultra Wideband (UWB) band operating under the IEEE 802.15.4 protocol and/or other ultra wideband communication protocols; communication bands under the 3GPP family of wireless communication standards; a communication band under the IEEE 802.Xx family of standards, and/or any other desired band of interest.

Fig. 2 is a diagram showing exemplary components within the wireless circuit 24. As shown in fig. 2, the wireless circuitry 24 may include a processor such as the processor 26, radio Frequency (RF) transceiver circuitry such as the RF transceiver 28, radio frequency front end circuitry such as the radio frequency Front End Module (FEM) 40, and an antenna 42. Processor 26 may be a baseband processor, an applications processor, a general purpose processor, a microprocessor, a microcontroller, a digital signal processor, a host processor, dedicated signal processing hardware, a power management unit, or other type of processor. Processor 26 may be coupled to transceiver 28 by way of path 34. Transceiver 28 may be coupled to antenna 42 via radio frequency transmission line path 36. The radio frequency front end module 40 may be disposed on the radio frequency transmission line path 36 between the transceiver 28 and the antenna 42.

In the example of fig. 2, the wireless circuitry 24 is shown to include only a single processor 26, a single transceiver 28, a single front-end module 40, and a single antenna 42 for clarity. In general, the wireless circuitry 24 may include any desired number of processors 26, any desired number of transceivers 36, any desired number of front-end modules 40, and any desired number of antennas 42. Each processor 26 may be coupled to one or more transceivers 28 by a respective path 34. Each transceiver 28 may include a transmitter circuit 30 configured to output an uplink signal to an antenna 42, may include a receiver circuit 32 configured to receive a downlink signal from the antenna 42, and may be coupled to one or more antennas 42 through respective radio frequency transmission line paths 36. Each radio frequency transmission line path 36 may have a respective front end module 40 disposed thereon. If desired, two or more front end modules 40 may be disposed on the same radio frequency transmission line path 36. One or more of the radio frequency transmission line paths 36 in the wireless circuit 24 may be implemented without any front-end modules disposed thereon, if desired.

The radio frequency transmission line path 36 may be coupled to an antenna feed on the antenna 42. The antenna feed may, for example, include a positive antenna feed terminal and a ground antenna feed terminal. The radio frequency transmission line path 36 may have a positive transmission line signal path coupled to a positive antenna feed terminal on the antenna 42. The radio frequency transmission line path 36 may have a ground transmission line signal path coupled to a ground antenna feed terminal on the antenna 42. This example is illustrative, and in general, the antenna 42 may be fed using any desired antenna feed scheme. If desired, the antenna 42 may have multiple antenna feeds coupled to one or more radio frequency transmission line paths 36.

The radio frequency transmission line path 36 may include a transmission line for routing radio frequency antenna signals within the device 10 (fig. 1). The transmission lines in the device 10 may include coaxial cables, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from a combination of these types of transmission lines, and the like. Transmission lines in the device 10, such as in the radio frequency transmission line path 36, may be integrated into rigid and/or flexible printed circuit boards.

When performing wireless transmission, the processor 26 may provide a transmit signal (e.g., a digital or baseband signal) to the transceiver 28 via path 34. Transceiver 28 may also include circuitry for converting the transmit (baseband) signals received from processor 26 to corresponding radio frequency signals. For example, transceiver circuitry 28 may include mixer circuitry for up-converting (or modulating) a transmit (baseband) signal to radio frequency prior to transmission through antenna 42. The example of fig. 2 in which the processor 26 communicates with the transceiver 28 is illustrative. In general, the transceiver 28 may communicate with one or more processors within the baseband processor, applications processor, general purpose processor, microcontroller, microprocessor, or circuitry 18. Transceiver circuitry 28 may also include digital-to-analog converter (DAC) circuitry and/or analog-to-digital converter (ADC) circuitry for converting signals between the digital domain and the analog domain. Transceiver 28 may transmit radio frequency signals through antenna 42 using Transmitter (TX) 30 via radio frequency transmission line path 36 and front end module 40. The antenna 42 may transmit the radio frequency signal to external wireless equipment by radiating the radio frequency signal into free space.

Front End Module (FEM) 40 may include radio frequency front end circuitry that operates on radio frequency signals that are transmitted (transmitted and/or received) through radio frequency transmission line path 36. For example, FEM 40 may include front-end module (FEM) components such as radio frequency filter circuitry 44 (e.g., low pass filter, high pass filter, notch filter, band pass filter, multiplexing circuitry, diplexer circuitry, triplexer circuitry, etc.), switching circuitry 46 (e.g., one or more radio frequency switches), radio frequency amplifier circuitry 48 (e.g., one or more power amplifier circuitry 50 and/or one or more low noise amplifier circuitry 52), impedance matching circuitry (e.g., circuitry that helps match the impedance of antenna 42 to the impedance of radio frequency transmission line 36), antenna tuning circuitry (e.g., a network of capacitors, resistors, inductors, and/or switches that adjust the frequency response of antenna 42), radio frequency coupler circuitry, charge pump circuitry, power management circuitry, digital control and interface circuitry, and/or any other desired circuitry that operates on radio frequency signals transmitted and/or received by antenna 42. Each of the front end module components may be mounted to a common (shared) substrate, such as a rigid printed circuit board substrate or a flexible printed circuit substrate. The various front-end module components may also be integrated into a single integrated circuit chip, if desired. Amplifier circuit 48 and/or other components in front-end 40, such as filter circuit 44, may also be implemented as part of transceiver circuit 28, if desired.

Filter circuitry 44, switching circuitry 46, amplifier circuitry 48, and other circuitry may be disposed along radio frequency transmission line path 36, may be incorporated into FEM 40, and/or may be incorporated into antenna 42 (e.g., to support antenna tuning, to support operation in a desired frequency band, etc.). These components (sometimes referred to herein as antenna tuning components) may be adjusted (e.g., using control circuitry 14) to adjust the frequency response and wireless performance of antenna 42 over time.

Transceiver 28 may be separate from front-end module 40. For example, transceiver 28 may be formed on another substrate such as a main logic board of device 10, a rigid printed circuit board, or a flexible printed circuit that is not part of front-end module 40. Although, for clarity, in the example of fig. 1, control circuit 14 is shown separate from wireless circuit 24, wireless circuit 24 may include processing circuitry that forms part of processing circuit 18 and/or memory circuitry that forms part of memory circuit 16 of control circuit 14 (e.g., portions of control circuit 14 may be implemented on wireless circuit 24). As one example, the processor 26 and/or portions of the transceiver 28 (e.g., a host processor on the transceiver 28) may form part of the control circuit 14. The control circuitry 14 (e.g., portions of the control circuitry 14 formed on the processor 26, portions of the control circuitry 14 formed on the transceiver 28, and/or portions of the control circuitry 14 separate from the radio circuitry 24) may provide control signals (e.g., through one or more control paths in the device 10) that control the operation of the front-end module 40.

Transceiver circuitry 28 may include processing WLAN communications bands (e.g.,(IEEE 802.11) or other WLAN communication bands) such as the 2.4GHz WLAN band (e.g., 2400MHz to 2480 MHz), the 5GHz WLAN band (e.g., 5180MHz to 5825 MHz),/>6E band (e.g., 5925MHz to 7125 MHz) and/or other/>Wireless local area network transceiver circuitry for a frequency band (e.g., 1875MHz to 5160 MHz); treatment 2.4GHz/>Wireless personal area network transceiver circuitry for a band or other WPAN communication band; a cellular telephone transceiver circuit that processes cellular telephone frequency bands (e.g., a frequency band of about 600MHz to about 5GHz, a 3G frequency band, a 4G LTE frequency band, a 5G new air interface frequency range 1 (FR 1) frequency band below 10GHz, a 5G new air interface frequency range 2 (FR 2) frequency band between 20GHz and 60GHz, etc.); near Field Communication (NFC) transceiver circuitry to process a near field communication band (e.g., 13.56 MHz); satellite navigation receiver circuitry that processes satellite navigation bands (e.g., GPS bands of 1565MHz to 1610MHz, global satellite navigation system (GLONASS) bands, beidou satellite navigation system (BDS) bands, etc.); ultra Wideband (UWB) transceiver circuitry that processes communications using IEEE 802.15.4 protocols and/or other ultra wideband communication protocols; and/or any other desired radio frequency transceiver circuitry for covering any other desired communication band of interest.

The wireless circuitry 24 may include one or more antennas, such as antenna 42. Any desired antenna structure may be used to form the antenna 42. For example, the antenna 42 may be an antenna having a resonating element formed from a loop antenna structure, a patch antenna structure, an inverted-F antenna structure, a slot antenna structure, a planar inverted-F antenna structure, a helical antenna structure, a monopole antenna, a dipole, a mixture of these designs, or the like. The two or more antennas 42 may be arranged in one or more phased antenna arrays (e.g., for transmitting radio frequency signals at millimeter wave frequencies). Parasitic elements may be included in the antenna 42 to adjust antenna performance. The antenna 42 may be provided with a conductive cavity that supports an antenna resonating element of the antenna 42 (e.g., the antenna 42 may be a back cavity antenna such as a back cavity slot antenna).

As described above, the front-end module 40 may include one or more Power Amplifier (PA) circuits 50 in the transmit (uplink) path. The power amplifier 50 (sometimes referred to as a radio frequency power amplifier, transmission amplifier, or amplifier) may be configured to amplify radio frequency signals without changing the signal shape, format, or modulation. For example, amplifier 50 may be used to provide 10dB gain, 20dB gain, 10dB-20dB gain, less than 20dB gain, more than 20dB gain, or other suitable amount of gain.

Designing a satisfactory radio frequency power amplifier for an electronic device can be challenging. In some applications, the radio frequency power amplifier may be implemented as a Load Line Modulated (LLM) radio frequency power amplifier. A load line modulated radio frequency power amplifier (sometimes referred to herein as a load modulated radio frequency amplifier) may have an adjustable load component, including an adjustable load line, that is tuned to provide different gain profiles. However, the adjustable load component has a limited modulation (tuning) range. In other words, the tuning of the adjustable load component may provide load line adaptation only for a sub-range of the instantaneous signal envelope of the baseband signal generated at the output of the processor 26.

According to one embodiment, the wireless circuit 24 may be provided with a load line modulated amplifier circuit comprising a plurality of adjustable load components that each provide coverage of a different sub-range of the instantaneous signal envelope. The plurality of adjustable load components may be tuned using different control signals. The control signals may be selected such that the various tuning ranges of the adjustable load components may be joined together to provide a wider (wider) tuning range.

Fig. 3 is a diagram of an exemplary wireless circuit 24 having a load line modulation amplifier circuit 50 with a plurality of adjustable load components that each provide a different tuning (modulation) range. As shown in fig. 3, the wireless circuit 24 may include a processor 26 configured to generate a baseband signal, a data converter such as a digital-to-analog converter (DAC) 66, an up-conversion circuit such as an up-converter 68, a load line modulated radio frequency power amplifier circuit such as the amplifier circuit 50, and an antenna 42 configured to radiate radio frequency signals output from the amplifier circuit 50.

Processor 26 may represent one or more processors, such as a baseband processor, an applications processor, a digital signal processor, a microcontroller, a microprocessor, a Central Processing Unit (CPU), a programmable device, a combination of these circuits, and/or one or more processors within circuit 18. The processor 26 may be configured to generate a digital (baseband) signal BB. The signal BB generated at the output of the processor 26 is sometimes referred to as baseband signal, digital signal or transmit signal. As examples, the digital signals generated by the processor 26 may include in-phase (I) and quadrature-phase (Q) signals, radius and phase signals, or other digitally encoded signals.

The digital baseband signal output from the processor 26 may be converted from the digital domain to the analog domain using a digital-to-analog converter 66 and then up-converted (modulated) to radio frequencies using an up-converter 68 from the baseband frequency range (which is typically in the range of hundreds of kHz to hundreds of MHz) to radio frequencies in the range of hundreds of MHz or GHz. The up-converter 68 is sometimes referred to as a radio frequency modulator or radio frequency mixer.

The upconverted radio frequency signal may be fed as an input to a Radio Frequency (RF) amplifier circuit 50. The amplifier circuit 50 may include an amplifier 60 having an input configured to receive the upconverted radio frequency signal from the modulator 68 and having an output coupled to a plurality of adjustable load components, including but not limited to a first adjustable load component Z1 and a second adjustable load component Z1. The adjustable load component Z1 may have a first terminal coupled to at least the output of the amplifier 60 via a first coupling circuit 62-1 and a second terminal coupled to a ground power supply line 64 (e.g., a ground line on which a ground power supply voltage is provided). The adjustable load component Z2 may have a first terminal coupled to the output of the amplifier 60 via at least a second coupling circuit 62-2 and a second terminal coupled to a ground line 64.

The adjustable load components Z1 and Z2 may each be a tunable resistance (e.g., an adjustable resistor), a tunable capacitance (e.g., an adjustable capacitor), a tunable inductance (e.g., an adjustable inductor), other reactive or lossless electrical components, combinations of these components, or other adjustable impedance components. The example of fig. 3 is illustrative, wherein the load line modulated amplifier circuit 50 includes at least two adjustable impedance components Z1 and Z2. In general, the amplifier circuit 50 may include three or more adjustable impedance components, four or more adjustable impedance components, 5 to 10 adjustable impedance components, or more than 10 adjustable impedance components, each providing a different tuning/modulation range.

Adjusting the load components Z1 and Z2 may tune the load impedance seen by the amplifier 60 from its output (see, e.g., load impedance Z _L seen by the amplifier core), which may shift the gain curve response of the amplifier circuit 50. The adjustable load section Z1 may be controlled using a first control voltage signal Vc1 (sometimes referred to as a first load tuning control signal) and the adjustable load section Z2 may be controlled using a second control voltage signal Vc2 (sometimes referred to as a second load tuning control signal). The first control signal Vc1 may be output from the first buffer or voltage driver 72-1 based on the first envelope signal. The second control signal Vc2 may be output from the second buffer or voltage driver 72-2 based on a second envelope signal that is offset from the first envelope signal by an offset. In the example of fig. 3, the control signals Vc1 and Vc2 are each generated based on the envelope signal Vctr output from the control signal generator 70. The control signal (voltage) Vctr may be fed directly to the input of the buffer 72-1. On the other hand, the control voltage Vctr may be fed to the input of the buffer 72-2 via the voltage biasing element 74. Operating in this manner, the control signal Vc2 output from the buffer 72-2 may be offset from the control signal Vc1 by a voltage offset Vos (e.g., the second buffer 72-2 is configured to receive an offset version of the control voltage Vctr). The voltage bias Vos may be a predetermined voltage, a fixed voltage, or an adjustable voltage. The bias between the two load tuning control signals shown as voltages is exemplary. In general, biasing may be implemented in a non-voltage domain (such as in the digital domain prior to digital-to-analog conversion). In such a scenario, buffer 72-1 may be a first digital-to-analog (D/A) conversion circuit and buffer 72-2 may be a second digital-to-analog (D/A) conversion circuit.

The control signal generator 70 may receive the baseband signal BB from the processor 26 and output a corresponding control voltage Vctr. The control voltage Vctr may be an envelope signal of the baseband signal BB or a radio frequency signal input to the amplifier circuit 50. The control signal generator 70 may include an absolute value function generator, a signal shaping function, a linear or nonlinear transformation function, a combination of these functions, or other signal conditioning function for outputting the control voltage Vctr. If desired, control signal generator 70 may also include a non-linear estimator (e.g., an amplifier non-linear estimator modeling the non-linear behavior of amplifier 50), an amplifier load response estimator (e.g., an amplifier load response estimator that implements a baseband model of the frequency dependent response of the load at the output of amplifier 50), and/or other circuitry that may additionally help tune components Z1 and Z2 for optimal performance and efficiency. The control voltage Vctr may be based on or derived from the instantaneous signal envelope of the baseband signal BB or the instantaneous signal envelope of the radio frequency signal at the input of the amplifier circuit 50. The control voltage Vctr may therefore sometimes be referred to as an envelope signal. For example, the first control signal Vc1 may be generated based on a first sub-range of the envelope signal Vctr, while the second control signal Vc2 may be generated based on a second sub-range of the envelope signal Vctr, where Vc1 and Vc2 are offset by a fixed or adjustable offset. By offsetting the control signal Vc2 by an offset amount with respect to the control signal Vc1, the adjustable load elements Z1 and Z2 may react to different regions or sub-ranges, respectively, of the total voltage range of the instantaneous signal envelope of the baseband or RF signal.

The wireless circuitry 24 may optionally include an Adaptive Power Tracking (APT) circuit 76. The adaptive power tracking circuit 76 may receive the baseband signal BB from the processor 26 and output a control signal to the amplifier 60 via a control path 78. Unlike Envelope Tracking (ET) techniques, which constantly change the supply voltage of the amplifier 60, the adaptive power tracking circuit 76 may be used to provide a relatively constant supply voltage to the amplifier 60. The adaptive power tracking circuit 76 may adjust the amplifier 60 to operate in different power modes. When the total power level of the radio frequency signal reaching the input of the amplifier circuit 50 is low, the adaptive power tracking circuit 76 may provide a relatively high supply voltage to the amplifier 60 so that the amplifier 60 may operate in a high power mode. Conversely, when the total power level of the radio frequency signal reaching the input of the amplifier circuit 50 is low, the adaptive power tracking circuit 76 may provide a relatively low supply voltage to the amplifier 60 so that the amplifier 60 may operate in a low power mode. In general, the adaptive power tracking circuit 76 may provide fine power mode tuning capabilities, coarse power mode tuning capabilities, and/or may direct the amplifier 60 to operate in any suitable number of power modes.

Fig. 4 is a circuit diagram illustrating one suitable implementation of a portion of wireless circuitry 24. In the example of fig. 4, coupling circuits 62-1 and 62-2 may be implemented as transformers. The first coupling circuit 62-1 may include a primary coil (winding) L1a coupled to the output of the amplifier 60 and a secondary coil (winding) L1b coupled to the antenna 42. Specifically, the secondary coil L1b may have a first terminal coupled to the antenna 42 and a second terminal coupled in series with the first adjustable load member Z1. The second coupling circuit 6202 may include a primary coil (winding) L2a and a secondary coil (winding) L2b. The primary coil L2a may have a first terminal coupled to the first coupling circuit 62-1 and a second terminal coupled to the first adjustable load member Z1. The secondary coil L2b may have a first terminal coupled to a power line (e.g., a ground line as shown in fig. 4, or alternatively, a positive power line) and a second terminal coupled to a second adjustable load member Z2. The use of transformers as the coupling circuits 62-1 and 62-2 is exemplary. Other types of radio frequency coupling structures may be employed if desired.

In fig. 4, the first voltage driver circuit 72-1 may be implemented as a first unity gain buffer 73-1 (e.g., an operational amplifier connected in a unity gain configuration), while the second voltage driver circuit 72-2 may be implemented as a second unity gain buffer 73-2. Configured in this manner, voltage drivers 72-1 and 72-2 may gain a corresponding control voltage through them. The use of a unity gain buffer is exemplary. Other types of buffers or driver circuits providing a voltage gain equal to one, greater than one, or less than one may be employed to drive control signals Vc1 and Vc2, if desired.

The embodiment of fig. 4 is exemplary in which adjustable load components Z1 and Z2 are coupled to the output of amplifier 60 via first coupling circuit 62-1 and second coupling circuit 62-2. In other embodiments, various adjustable load components may be coupled to the output of amplifier 60 via a single (joint) coupling circuit. For example, adjustable load components Z1 and Z2 may be coupled to the output of amplifier 60 via a multi-winding inductor or transformer having a primary coil (winding) connected to the output port of amplifier 60, a first secondary coil (winding) connected to adjustable load component Z1, and a second secondary coil (winding) connected to adjustable load component Z2. In general, such a multi-winding inductor or transformer may include any number of secondary coils (windings) for coupling to any desired number of adjustable load components.

Fig. 5 is a graphical representation of amplifier load impedance Z _L plotted as a function of control voltage signal for tuning adjustable load components Z1 and Z2 of fig. 4. As shown in fig. 5, the control signal Vc1 may first start to increase when Vctr exceeds the first voltage level vctr_x. Adjusting the load tuning control signal Vc1 may tune the first load element Z1 to change the amplifier load impedance between the impedance values Z _L0 and Z _L1. Due to the voltage bias, the control signal Vc2 may only start to increase when Vctr exceeds a second voltage level Vctr_y that is greater than Vctr_x. The voltage vctr_y may be greater than the voltage vctr_x by the offset Vos. By biasing Vc2 relative to Vc1, adjustable load elements Z1 and Z2 may have an offset tuning range. Adjusting the load tuning control signal Vc2 may tune the second load element Z2 to effectively change the amplifier load impedance between the impedance values Z _L1 and Z _L2 (see, e.g., the total voltage tuning curve vc_total).

Thus, using two separately adjustable load components controlled by different voltage signals may provide a wider effective overall tuning range than either of the adjustable load components itself. In other words, tuning the first load component Z1 using the control signal Vc1 may provide a first tuning range of a first portion of the instantaneous signal envelope of the baseband or RF signal (e.g., covering a first sub-range of the small signal envelope), while tuning the second load component Z2 using the control signal Vc2 may provide a second tuning range of a second portion of the instantaneous signal envelope of the baseband or RF signal (e.g., covering a second sub-range of the large signal envelope). The first tuning range and the second tuning range may together provide an extended or wider effective modulation range covering all possible or most of the signal envelope values.

The example of fig. 5 shows a scenario in which the tuning ranges associated with Vc1 and Vc2 are non-overlapping. As shown in fig. 5, the amplifier load impedance increases from Z _L0 to Z _L1 by increasing Vc1 only, and Vc2 rises immediately after Vc1 to increase the amplifier load impedance from Z _L1 to Z _L2, with no discontinuities or kinks in the total effective impedance curve corresponding to vc_total. In practice, however, the tuning ranges associated with Vc1 and Vc2 may at least partially overlap (see, e.g., fig. 6). This may be the result of curved transitions such as curved portion 80 in the Vc1 profile and curved portion 82 in the Vc2 profile. This may be shown as a slight deviation 84 in the total effective impedance curve corresponding to Vc_total. In any event, overlapping tuning ranges may provide a wider effective total modulation range for the load line modulated amplifier.

The embodiment of fig. 3 is exemplary, wherein the amplifier circuit 50 is provided with at least two individually adjustable load components Z1 and Z2. Fig. 7 shows another embodiment in which the amplifier circuit 50 is provided with more than two adjustable load components. As shown in fig. 7, the amplifier 60 may be coupled to at least three adjustable load components Z1, Z2, and Z3 using a coupling circuit 62. The coupling circuit 62 may be a transformer-based coupler, a tightly coupled transmission line-based coupling structure, or other types of radio frequency signal coupling circuits.

The adjustable load section Z1 may receive the first control signal Vc1 from the control signal generator 70. The adjustable load section Z2 may receive the second control signal Vc2 from the control signal generator 70. The adjustable load section Z3 may receive a third control signal Vc3 from the control signal generator 70. The control signals Vc1, vc2 and Vc3 may each be based on or derived from an instantaneous signal envelope of the baseband signal BB received from the processor 26 or an instantaneous signal envelope of the RF signal at the input of the amplifier circuit 50. Signals Vc1, vc2 and Vc3 may optionally be offset relative to each other by a fixed or adjustable voltage offset. In the example of fig. 7, the control signal generator 70 comprises three separate generator sub-circuits for outputting Vc1, vc2 and Vc3, respectively. In other embodiments, a single generator may output Vctr, one of which is continuously fed with Vc1, while additional voltage biases may be introduced to continuously generate Vc2 and Vc3 in a manner similar to the embodiments of FIGS. 3 and 4.

Configured in this way, the adjustable load component Z1 can be tuned using Vc1 to provide a first tuning range covering a first sub-range of the instantaneous signal envelope of the baseband or RF signal; the adjustable load component Z2 is tunable using Vc2 to provide a second tuning range covering a second sub-range of the instantaneous signal envelope, the second tuning range not overlapping or partially overlapping the first tuning range; the adjustable load component Z3 may be tuned using Vc3 to provide a third tuning range covering a third sub-range of the instantaneous signal envelope, the third tuning range not overlapping or partially overlapping with the second tuning range. Operating in this manner, the load line modulated amplifier circuit 50 may exhibit a wider (extended) total tuning range that is the sum of the first tuning range, the second tuning range, and the third tuning range.

The example of fig. 7 is illustrative, wherein the load line modulation amplifier circuit 50 includes at least three adjustable load components Z1, Z2, and Z3. In general, the amplifier circuit 50 may include more than three adjustable load components, four or more adjustable load components, 5 to 10 adjustable load components, 10 to 20 adjustable load components, or more than 20 adjustable load components, each providing a different tuning/modulation range corresponding to a different sub-range of the total voltage range of the instantaneous signal envelope of the baseband or RF signal.

As described above in connection with fig. 3, the wireless circuit 24 may optionally include an adaptive power tracking circuit 76 that may be used to operate the load line modulated amplifier in a plurality of different power modes. Fig. 8 is a state diagram illustrating how a load line modulated amplifier circuit 50 of the type described in connection with fig. 2-7 may be capable of operating in at least a first power mode 90, a second power mode 92, and a third power mode 94.

In the first power mode 90, the adaptive power tracking circuit 76 may provide a relatively low supply voltage to the amplifier 60 such that the amplifier 60 operates in a low power mode. In this mode 90, the adjustable load components Z1 and Z2 (and optional additional load components) are individually tunable using Vc1 and Vc2 to provide a first total load tuning range when the amplifier is operating in a low power mode.

In the second power mode 92, the adaptive power tracking circuit 76 may provide an intermediate (medium) supply voltage to the amplifier 60 such that the amplifier 60 operates in the medium (normal) power mode. In this mode 92, the adjustable load components Z1 and Z2 (and optional additional load components) are individually tunable using Vc1 and Vc2 to provide a second total load tuning range when the amplifier is operating in a medium power mode. The second total load tuning range may not overlap or only partially overlap with the first total load tuning range.

In the third power mode 94, the adaptive power tracking circuit 76 may provide a high (boost) supply voltage to the amplifier 60 such that the amplifier 60 operates in the high power mode. In this mode 94, the adjustable load components Z1 and Z2 (and optional additional load components) may be individually tuned using Vc1 and Vc2 to provide a third total load tuning range when the amplifier is operating in the high power mode. The third total load tuning range may not overlap or only partially overlap the first total load tuning range and the second total load tuning range. By combining the flexible power modes provided by the adaptive power tracking circuit 76 with the extended tuning range provided by the plurality of adjustable load components, the LLM amplifier circuit can exhibit a much wider tuning capability across a wide range of power modes.

The example of fig. 8 showing only three different power modes is illustrative. In general, the adaptive power tracking circuit 76 may direct the LLM amplifier to operate in more than three different power modes, 3 to 10 different power modes, 10 to 20 different power modes, 20 to 100 different power modes, or more than 100 different power modes. In each of the various power modes, two or more adjustable load components, each covering a different sub-range of the instantaneous signal envelope of the baseband or RF signal, may be used to extend the total effective tuning range.

The methods and operations described above in connection with fig. 1-8 may be performed by components of device 10 using software, firmware, and/or hardware (e.g., dedicated circuitry or hardware). The software code for performing these operations may be stored on a non-transitory computer-readable storage medium (e.g., a tangible computer-readable storage medium) stored on one or more of the components of the device 10 (e.g., the storage circuitry 16 and/or the wireless communication circuitry 24 of fig. 1). The software code may sometimes be referred to as software, data, instructions, program instructions, or code. The non-transitory computer readable storage medium may include a drive, non-volatile memory such as non-volatile random access memory (NVRAM), a removable flash drive or other removable medium, other types of random access memory, and the like. The software stored on the non-transitory computer readable storage medium may be executed by processing circuitry (e.g., processing circuitry in wireless communication circuitry 24, processing circuitry 18 of fig. 1, etc.) on one or more of the components of device 10. The processing circuitry may include a microprocessor, an application processor, a digital signal processor, a Central Processing Unit (CPU), an application specific integrated circuit with processing circuitry, or other processing circuitry.

According to one embodiment, there is provided a radio circuit including: a radio frequency amplifier configured to receive a radio frequency signal generated from a baseband signal; a first adjustable load component coupled to an output of the radio frequency amplifier; a second adjustable load component coupled to the output of the radio frequency amplifier; and a control signal generator configured to output one or more control signals for tuning the first and second adjustable load components based on an envelope of the baseband signal or the radio frequency signal.

According to another embodiment, the first adjustable load component is configured to provide a first impedance tuning range for a first sub-range of the envelope, and the second adjustable load component is configured to provide a second impedance tuning range for a second sub-range of the envelope different from the first sub-range.

According to another embodiment, the wireless circuit includes: a first coupling circuit coupled between the output of the radio frequency amplifier and the first adjustable load component; and a second coupling circuit coupled between the output of the radio frequency amplifier and the second adjustable load component.

According to another embodiment, the second coupling circuit is coupled between the first coupling circuit and the second adjustable load member.

According to another embodiment, the first coupling circuit comprises a first transformer and the second coupling circuit comprises a second transformer.

According to another embodiment, the first transformer comprises: a first primary coil coupled to the output of the radio frequency amplifier; and a first secondary coil having a first terminal coupled to the antenna and having a second terminal coupled to the first adjustable load component via the second transformer.

According to another embodiment, the second transformer comprises: a second primary coil having a first terminal coupled to the first secondary coil and having a second terminal coupled to the first adjustable load member; and a second secondary coil having a first terminal coupled to the second adjustable load member and having a second terminal coupled to a power line.

According to another embodiment, the wireless circuit includes: and a coupling circuit coupled between the output of the radio frequency amplifier and the first and second adjustable load components.

According to another embodiment, the control signal generator is configured to output a first control signal for tuning the first adjustable load component based on a first envelope signal and to output a second control signal for tuning the second adjustable load component based on a second envelope signal, and the second envelope signal is offset from the first envelope signal by an offset.

According to another embodiment, the wireless circuit includes: a third adjustable load component coupled to the output of the radio frequency amplifier and configured to receive the one or more control signals from the control signal generator.

According to another embodiment, the control signal generator comprises an absolute value function circuit.

According to another embodiment, the first adjustable load member and the second adjustable load member comprise adjustable impedances.

According to one embodiment, there is provided a method of operating a radio circuit, the method comprising: receiving, at an amplifier, a radio frequency signal generated based on the baseband signal; tuning a first adjustable load component coupled to an output of an amplifier using a first load tuning control signal derived from an envelope of the baseband signal or the radio frequency signal; and tuning a second adjustable load component coupled to the output of the amplifier using a second load tuning control signal derived from the envelope of the baseband signal or the radio frequency signal.

According to another embodiment, the method comprises: providing a first impedance tuning range for a first sub-range of the envelope using the first adjustable load component; and using the second adjustable load component to provide a second impedance tuning range for a second sub-range of the envelope that is different from the first impedance tuning range.

According to another embodiment, the method comprises: generating a control signal based on the baseband signal or the envelope of the radio frequency signal with a control signal generator; receiving the control signal with a first conversion circuit and outputting the first load tuning control signal based on a first range of the control signal; and outputting, with a second switching circuit, the second load tuning control signal based on a second range of the control signal, the second load tuning control signal being offset from the first load tuning control signal by a fixed or adjustable bias.

According to another embodiment, the method comprises: coupling a third adjustable load component to the output of the amplifier; and tuning the third adjustable load component using a third load tuning control signal derived from the envelope of the baseband signal or the radio frequency signal.

According to one embodiment, there is provided an electronic device including: one or more processors configured to generate a baseband signal; an up-converter configured to convert the baseband signal to a radio frequency signal; and a load line modulation amplifier circuit configured to amplify the radio frequency signal, the load line modulation amplifier circuit comprising: an amplifier configured to receive the radio frequency signal, a first adjustable load component coupled to an output of the amplifier, and a second adjustable load component coupled to the output of the amplifier.

According to another embodiment, the first adjustable load component is configured to provide a first tuning range covering a first sub-range of the instantaneous signal envelope of the baseband signal or the radio frequency signal, and the second adjustable load component is configured to provide a second tuning range covering a second sub-range of the instantaneous signal envelope of the baseband signal or the radio frequency signal, the first tuning range and the second tuning range combining to provide an extended tuning range for the load line modulated amplifier circuit.

According to another embodiment, the load line modulation amplifier circuit includes: a coupling circuit is coupled between the output of the amplifier and the antenna and is configured to couple the first and second adjustable load components to the output of the amplifier.

According to another embodiment, the electronic device includes: a control signal generator configured to receive the baseband signal and generate corresponding control signals for tuning the first and second adjustable load components; a first buffer configured to receive the control signal and generate a first load tuning control signal for tuning the first adjustable load component; and a second buffer configured to receive the shifted version of the control signal and to generate a second load tuning control signal for tuning the second adjustable load component.

The foregoing is merely illustrative and various modifications may be made to the embodiments. The foregoing embodiments may be implemented independently or may be implemented in any combination.

Claims

1.A wireless circuit, comprising:

A radio frequency amplifier configured to receive a radio frequency signal generated from a baseband signal;

A first adjustable load component coupled to an output of the radio frequency amplifier;

a second adjustable load component coupled to the output of the radio frequency amplifier; and

A control signal generator configured to output one or more control signals for tuning the first and second adjustable load components based on an envelope of the baseband signal or the radio frequency signal.

2. The wireless circuit of claim 1, wherein the first adjustable load component is configured to provide a first impedance tuning range for a first sub-range of the envelope, and wherein the second adjustable load component is configured to provide a second impedance tuning range for a second sub-range of the envelope that is different from the first sub-range.

3. The wireless circuit of claim 1, further comprising:

a first coupling circuit coupled between the output of the radio frequency amplifier and the first adjustable load component; and

A second coupling circuit coupled between the output of the radio frequency amplifier and the second adjustable load component.

4. The wireless circuit of claim 3, wherein the second coupling circuit is coupled between the first coupling circuit and the second adjustable load component.

5. The wireless circuit of claim 3, wherein the first coupling circuit comprises a first transformer, and wherein the second coupling circuit comprises a second transformer.

6. The wireless circuit of claim 5, wherein the first transformer comprises:

a first primary coil coupled to the output of the radio frequency amplifier; and

A first secondary coil having a first terminal coupled to an antenna and having a second terminal coupled to the first adjustable load member via the second transformer.

7. The wireless circuit of claim 6, wherein the second transformer comprises:

A second primary coil having a first terminal coupled to the first secondary coil and having a second terminal coupled to the first adjustable load member; and

A second secondary coil having a first terminal coupled to the second adjustable load member and having a second terminal coupled to a power line.

8. The wireless circuit of claim 1, further comprising:

a coupling circuit is coupled between the output of the radio frequency amplifier and the first and second adjustable load components.

9. The wireless circuit of claim 1, wherein the control signal generator is configured to output a first control signal for tuning the first adjustable load component based on a first envelope signal and to output a second control signal for tuning the second adjustable load component based on a second envelope signal, and wherein the second envelope signal is offset from the first envelope signal by an offset.

10. The wireless circuit of claim 1, further comprising:

A third adjustable load component coupled to the output of the radio frequency amplifier and configured to receive the one or more control signals from the control signal generator.

11. The wireless circuit of claim 1, wherein the control signal generator comprises an absolute value function circuit.

12. The wireless circuit of claim 1, wherein the first adjustable load component and the second adjustable load component comprise adjustable impedances.

13. A method of operating a wireless circuit, comprising:

Receiving, at an amplifier, a radio frequency signal generated based on the baseband signal;

Tuning a first adjustable load component coupled to an output of an amplifier using a first load tuning control signal derived from an envelope of the baseband signal or the radio frequency signal; and

A second adjustable load component coupled to the output of the amplifier is tuned using a second load tuning control signal derived from the envelope of the baseband signal or the radio frequency signal.

14. The method of claim 13, further comprising:

providing a first impedance tuning range for a first sub-range of the envelope using the first adjustable load component; and

The second adjustable load component is used to provide a second impedance tuning range for a second sub-range of the envelope that is different from the first impedance tuning range.

15. The method of claim 13, further comprising:

generating a control signal based on the envelope of the baseband signal or the radio frequency signal with a control signal generator;

Receiving the control signal with a first conversion circuit and outputting the first load tuning control signal based on a first range of the control signal; and

The second load tuning control signal is output with a second conversion circuit based on a second range of the control signal, the second load tuning control signal being offset from the first load tuning control signal by a fixed or adjustable bias.

16. The method of claim 13, further comprising:

coupling a third adjustable load component to the output of the amplifier; and

The third adjustable load component is tuned using a third load tuning control signal derived from the envelope of the baseband signal or the radio frequency signal.

17. An electronic device, comprising:

One or more processors configured to generate a baseband signal;

an up-converter configured to convert the baseband signal to a radio frequency signal; and

A load line modulation amplifier circuit configured to amplify the radio frequency signal, the load line modulation amplifier circuit comprising

An amplifier configured to receive the radio frequency signal,

A first adjustable load component coupled to the output of the amplifier, an

A second adjustable load component coupled to the output of the amplifier.

18. The electronic device of claim 17, wherein:

The first adjustable load component is configured to provide a first tuning range covering a first sub-range of an instantaneous signal envelope of the baseband signal or the radio frequency signal; and

The second adjustable load component is configured to provide a second tuning range covering a second sub-range of the instantaneous signal envelope of the baseband signal or the radio frequency signal, wherein the first tuning range and the second tuning range combine to provide an extended tuning range for the load line modulated amplifier circuit.

19. The electronic device defined in claim 17 wherein the load line modulation amplifier circuit further comprises: a coupling circuit coupled between the output of the amplifier and an antenna and configured to couple the first and second adjustable load components to the output of the amplifier.

20. The electronic device of claim 17, further comprising:

A control signal generator configured to receive the baseband signal and generate corresponding control signals for tuning the first and second adjustable load components;

A first buffer configured to receive the control signal and generate a first load tuning control signal for tuning the first adjustable load component; and

A second buffer configured to receive the shifted version of the control signal and to generate a second load tuning control signal for tuning the second adjustable load component.